Ruído e vibração na caixa de câmbio: soluções para engrenagens

Noise and vibration in the gearbox: solutions for gears

Do you notice any shifting noises and vibrations in the reduction box? This is a sign of a problem that must be resolved as soon as possible. A failure of the speed reducer mounted on the auger can cause the entire machine to stop. Any delay in production is costly and unpleasant. Definitely something worth avoiding.

Your shaft-mounted speed reducer is the sum of many interconnected parts. When everything is working perfectly, we tend to think of it as a single unit. However, when it breaks, multiple parts could be the problem. It is important to remember that gearbox noise and vibration can be caused by a variety of components or even a group of several.

There's a lot to sort out, but with a little troubleshooting we can narrow it down.

Inadequate fixation

Shaft-mounted gearboxes are fully supported by the shaft on which they are mounted. Without a torque arm installed, the resulting forces from the main engine would rotate the gearbox on said shaft. Not unlike a mounting flange for a C-face reducer, the torque arm allows forces to pass from the drive to the mounted shaft.

When a torque arm is installed incorrectly, the transmitted torque will no longer be fully directed to the driven shaft, leaving the remaining forces to create vibration within the transmission. It is essential to confirm that the torque arm is 90° to the centerline of the input and output shafts and that all fasteners have been tightened correctly.

AT at 90 degrees

Inadequate oil levels

Lubrication, lubrication, lubrication. A transmission system is full of moving parts. Without adequate lubrication, increased friction will allow wear to develop more quickly, which will naturally cause vibration and noise. These are the last problems, however, because a poorly lubricated system can develop more problems, resulting in destroyed parts and lost productivity.

Proper lubrication is key to keeping any mechanical system in good condition. In a gear reducer, the oil minimizes friction between the surfaces and transfers heat away from the contact area. Additionally, it also keeps the bearings and seals in good working order. When the oil level is low, unnecessary wear and tear causes premature wear of gears and bearings. These worn-out parts create noises and vibrations that you find difficult to ignore.

If you suspect your oil level may be low, it's worth checking the application guide. There are six mounting positions and different swivel and tilt levels. Each variant will require a different amount of oil, from 0.65 L to 25 L.

SMR oil levels

Premature gear wear

Along the same lines, premature wear of gears or bearings can cause unexpected gear movements, vibrations, and noise. Gear designs allow gears to operate with a certain amount of backlash or backlash between gear sets. Bearing designs allow operation with a certain internal clearance or end play. Excessive wear will increase these clearances and cause gears and bearings to move unevenly. Teeth can engage at strange, unintended angles, creating unknown forces that vibrate parts of your system.

There are several reasons why premature gear wear can occur. As you would expect, one of the most common is inadequate lubrication. If the oil is too thin, it will not provide the necessary protection to the gears and the resulting friction will wear them out prematurely.

Other problems will occur if the unit cannot withstand the mechanical or thermal forces to which it is exposed during operation. Each gearbox is rated to mechanically or thermally handle a specific amount of input power. Exceeding these ratings will cause premature wear. The only question is how long it will take before wear and tear turns into catastrophic failure.

If conditions in your location are more extreme than average, with higher temperatures, higher altitudes, or other complications, you will need to consider these variations in the guidelines. Excessive mechanical or thermal pressure on the gearbox can cause very rapid premature wear. Reselecting a drive with the appropriate service factor will avoid this scenario.

It is difficult to know the exact cause of gear or bearing damage, especially when the gearbox is still assembled. After checking lubrication levels and ensuring the proper service factor is being used, the final step is replacement. New gears and bearings, followed by careful reassembly and installation, should resolve any problems.

Undersized or bent shaft

When solving problems like vibration, the shaft is important. If the driven shaft is out of tolerance, the gearbox double tapered bushings will not be able to hold it securely. Any amount of unbalanced rotation and wobble within the bushings will cause vibration in the shaft-mounted helical gearbox.

If you think the shaft is the correct size but there appears to be rotation or wobble, check the tightness of the bushings. Fully tightened tapered bushings on a correctly sized shaft should eliminate problems as long as the torque arm is also aligned.

Likewise, the driven shaft must extend the entire length of the helical mount shaft reducer. If the shaft is not fully supported, the load transmitted will not be uniform. When this happens, the excessive load on one side of the gearbox will increase the pressure on the gears beyond what they were designed to handle. These high, unbalanced loads will wear out the gears, causing the noise and vibration we talked about in the gears section. In these situations it will be necessary to reposition the reduction gear on the driven shaft and replace the worn gears.

The tree's final consideration is depletion. A bent shaft, no matter how light, will cause imbalance during rotation. This eccentric rotation will cause vibrations. More importantly, it can accelerate the wear of each part of the internal structure of the helical mounting shaft speed reducer. It is essential to check the dimensions and runout of the driven shaft before installation. Nobody wants to replace a gearbox because of avoidable wear.

Worn or broken V-belts

Most shaft-mounted gearboxes are driven by an electric motor and a V-belt. For these units, the connection between the main motor and the gearbox must be as precise as possible. Over time, as V-belts wear, additional forces are generated in the system. These forces will cause imbalances in the system and therefore noise and vibrations in the gearbox. Any problem at the start of the drive can cause problems for the entire system, therefore, replacing worn belts is essential.

Suspended load

When excessive radial load is applied, too far from the support bearing, a condition known as radial loading occurs. This leads to excessive loads on the bearings and the risk of breakage of the input and output shafts.

OHL

The protruding load will quickly wear bearings and cause vibrations when a shaft bends or breaks. It is essential to mount the pulley and sprockets as close as possible to the gearbox body to limit these effects.

Inadequate connections

Noise from driven equipment is a potential cause that can be more difficult to resolve than others because it involves adjacent systems. A properly functioning unit is symbiotic, with each part depending on those around it to function properly. A failure in another system, such as a conveyor, may occur down the line.

Any external component that is not working properly could transmit the problem to your gearbox. For example, if the tension or alignment of the belt drive is incorrect, all movement beyond that drive will be affected. The same goes for gaskets or any components with fasteners or set screws.

If something is misaligned or not fully seated on the shaft, these vibrations can be amplified by mounting the gearbox to the shaft. If you have thoroughly examined your transmission system and found no problems, take a critical look at the parts connected to it.

Questions about managing transmission wear or troubleshooting unexpected transmission problems?

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